Receptacle



Feb. 5, 1957 s. s. STEVENS 2,780,401

RECEPTACLE Original Filed April 25, 1947 5 Sheets-Sheet 1 INVENTORJdmuel 619216196205.

ORNEY Feb. 5, 1957 v s. '51. STEVENS 2,780,401

A RECEPTACLE original Filed April 25, 1947 5 Sheets-sheet z INVENTORUnited States Patent() RECEPTACLE Samuel S. Stevens, Plattsburgh, N. Y.,assignor, by mesue assignments, to The Diamond Match Company, New York,N. Y., a corporation of Delaware Original application April 25, 1947,Serial No. 743,357. Divided and this application February 1, 1952,Serial No. 269,473

3 Claims. (Cl. 229-25) This application is a division of application,Serial No. 743,857, tiled April 25, 1947, which issued March 25, 1952,as Patent 2,590,221, on the method of making the receptacle of `thisinvention.

This invention relates to molded libre articles having an interior lineror exterior covering, or both, of an organic plastic to render the wallof the article impervious to vapors and liquids.

Without limiting the invention to an article for any specific use,reference may be made, for the purpose of illustration, to theemployment of this invention in connection with molded fibre receptaclessuitable for packaging frozen food products. For the successful andeffective packaging of such products, it is necessary to have a sturdypackage which will withstand machine handling incident to lling,packaging and sealing of the food product and one which will withstandrough handling in storage and delivery to the ultimate consumer.

It is also necessary that such a receptacle retain all of theconstituents of its contents and prevent the ingress or egress of fluidor vapors which would contaminate the product if coming from the outsideand would permit the loss of essential ingredients of the product ifallowed to escape from the inside. For example, it is both desirable andnecessary to retain within the package the water or moisture content ofthe product throughout the time when it is stored, so that when itreaches the consumer, it will be in exactly the same state and conditionas when it was packed.

In food packages of the type heretofore used for the packaging of frozenfoods, it has been customary to form the package from flat sheet stockor board by either or both cutting and folding it into receptacle form.If the sheet of material thus used is surface pretreated by ordinarycoating methods, prior to forming it into the receptacle, the formingoperation tends to break or weaken the coating along the fold lines orcreases, with the result that leakage or contamination of the productmay result. Furthermore, the folds or creases are ditlcult toetfectually seal against the passage of vapor and generally produceleakage areas with the result that the product may deteriorate or becomecontaminated. h

In contradistinction to the conventional prior practice, the containerof the present invention is molded and dried in its ultimate shapewithout creases, folds or score lines of any kind in its surface, sothat its wall may be of substantially uniform thickness throughout andconsequently of maximum `strength and rigidity for the stock employed.This container may be conveniently produced by suction molding it eitherfrom wood pulp orv other fibres, on a forming die to the desired shapeand thereafter drying the resulting article between hot drying dieswhile under pressure between said dies to produce a relatively smoothsurfaced article of ne texture and pleasing appearance. operationspreferably constitutes the body of the receptacle of this invention. t y

The container which results from these 7 In carrying out the presentinvention, I start with a molded container body of this character. Overthe interior or exterior of such body is then laminted a relatively thinsheet of an organic plastic which is adhered to said body at all pointswhere it comes in facial contact therewith. The preferred method ofadhering the sheet to the body is based upon certain discoveries which lhave made, to wit: if a relatively thin sheet of an organicthermoplastic is placed against a brous surface which is heated to atemperature sufficient to render the plastic llowable or tacky while theopposite surface of such sheet is maintained at a temperature below thesoftening point of the plastic and pressure is applied to the sheet, thethus heated surface stratum of the sheet will become fused and tend tolflow into the interstices of the contacting fibrous surface with theresult that, when the fibrous article is subsequently cooled, thatportion of the plastic which has entered into its structure will hardentherein and form therewith a permanent bond between the fibrous materialand the plastic sheet.

An important requirement of this procedure consists of maintaining atleast a portion of the thickness of the plastic sheet, remote from thebrous body, in solid unfused condition throughout the entire operationfor it has been found that, if the heat of such body penetrates entirelythrough the plastic sheet so as to fuse it for its entire thickness, thecontiguity of the sheet will be destroyed, pin holes will result and thesheet will not produce an impervious seal over the fibrous body to whichit is applied. Therefore, in the preferred manner of practising thepresent invention, the dies or other expedients, through the utilizationof which the organic sheet is applied to the fibrous surface, arepreferably cooled by water or air circulation or otherwise to maintainthat stratum of the organic sheet which engages therewith in its normalsolidified and unfused condition throughout.

ln compositing the bodyof the receptacle and its lining or coveringsheet, the body of the receptacle is preferably heated by an appropriatedie or dies, shaped to conforml with the body, so as to raise thetemperature of such body to the desired degree. The liner or coveringsheet is preferably formed or shaped to conform with the surface of thebody to whichf it is to be attached, on a complementary die which ispreferably provided with means for maintaining said die cool. After thecontainer body is heated and the plastic layer has been foirned Vasstated, they are brought together, preferably on substantiallyconforming complementary dies, to effect surface contact between thecontainer body and the plastic sheet and they are thereupon held in suchcontact until the surface stratum of the sheet which is in engagementwith the body shall have been softened or fused suiciently to provide aneffective bond while the remainder of the thickness of the sheet is keptbelow its fusion point. After fusion, with or without penetration, hasoccurred, the entire article is cooled to complete the assembly.

Features of the invention, other than those specified, will be apparentfrom the following detailed description and appended claims when read inconjunction with the accompanying drawings, wherein- Figure 1 shows thecross section through an illustrative type of molded fibre article towhich the liner covering sheet is to be applied. This article may beround, rectangular, square, or of any desirable shape.

Figure 2 shows a piece of flat sheet stock to be applied to the articleof Figure 1.

Figure 3 shows the finished article in cross section with the sheetapplied thereto as a liner.

Figure 4 shows the cross section of a heated die with the article ofFigure 1 thereon'.

Figure 5 shows the fibre article being held between two heated dies toinsure that the article is properly preheated, the outer die, or the dieon the bottom of the article, preventing the escape of heat applied bythe die heating the inner surface of the article.

Figure 6 shows the die on which the liner sheet is preformed. A s shown,the sheet has been laid on the at surface of the die and is held thereby suction or vacuum applied through the openings in this flat surface.

Figure 7 shows the die of Figure 6 with the sheet folded down over thesides of the die by means not shown, with the surplus material beingtaken up by folding the sheet over on itself. If desired, in the case ofa polygonal article, the portion of the sheet may be cut out at thecorners to facilitate its being shaped over the die of Figure 6.

Figure 8 shows the surplus material at the periphery of the sheet beingremoved, leaving the sheet of just the size to overlie and cover theinner surface of the article and the upper edge of the latter.

Figure 9 shows a transfer die for removing the article from the die ofFigure 4. This is preferably a suction or vacuum die.

Figure l() shows the article held between the transfer die of Figure 9and the sheet applying die of Figure 6. After removal from between thetwo dies shown in Figure l0, the receptacle will be in the finishedforrn shown in Figure 3.

According to this invention the plastic sheet may be made to covereither or both the inner and outer surfaces of the container body.However, for the purpose of concrete illustration, I will hereinafterdescribe the mode of applying such sheet to the inside and uppersurfaces of the container body so that it will serve as a linertherefor. It should be noted, however, that the same procedure may beutilized in applying said sheet to the exterior surfaces of such body.

The sheet material preferably used for this purpose in accordance withthis invention is in the nature of an organic plastic havingthermoplastic properties and while many such synthetic plastics may beemployed, the following may be referred to as illustrative, viz.:

To be efficient, inexpensive, and readily applicable to the body, thissheet, which is indicated in thedrawings by the reference character S,should be quite thin. The drawings show the sheet relatively thick forthe purpose of illustration, but, in practice, a very thin sheet ispreferably employed. v

The container body illustrated in Figure l and indicated by thereference character B is of molded fibre, as hereinbefore indicated, andit is of finished shape without folds or creases.

It is desirable to use a sheet S of minimum thickness, and, accordingly,I preferably employ a container body B of the kind which is suctionmolded'from 4a liquidlibre mixture, e. g., paper pulp, and subsequentlydie dried by pressing a heated die against at least the surface of thebody to which the sheet S is to be applied. This produces on the moldedand dic-dried article a smooth even surface well adapted to contactthroughout with a thin sheet of plastic material also having a smootheven surface.

To effectually unite the sheet S of Figure 2 and the container body B ofFigure l according to this invention to form a unitary structure whereinthe parts are substantially permanently adhered to one another, it isnecessary to bring the surface of the body to which the liner sheet S isto be applied to a temperature sufficiently high to fuse or soften suchsheet but not so high as to disintegrate it throughout its thicknesswhen manipulated as hereinafter described. The heating of the body maybc accomplished as a part of the method of making the body. However,this heating may be accomplished by utilizing the die 1 shown in Figure4, which is illustrated in this ligure as provided with heating channels2 through which a heating iiuid may be circulated or in which anelectrical heating element may be positioned for this purpose. Throughthe employment of such appropriate heating means, the die 1 may bebrought to and maintained at an optimum temperature which willmanifestly depend upon the particular thermoplastic of which the sheet Sis constituted.

To assist in the heating of the inner surface of the body B and toprotect the outer surface and prevent heat from being radiatedtherefrom, I provide a second die 3, shown in Figure 5, which serves topress the inner surface of the article against die I and hold it in firmcontact therewith. Die 3 may be heated by electric heating elements 4 orby amI other suitable means.

I so control the temperatures of dies 1 and 3 that the inner surface ofthe article will be heated to just the proper temperature to facilitatethe application of the sheet of thermoplastic material and to insure aneven and uniform adhesion thereto.

To pre-shape a preformed sheet of thermoplastic material, I provide adie structure 5 shown in Figure 6. This die structure has, in itsinterior, two chambers 6 and 7. From the chamber 7, passages or ducts 7alead to the upper or at surface of the die while passages 6a lead fromthe chamber 6 to the exterior sides of the die so that partial vacuum orsuction may be communicated to these exterior surfaces. Vacuum orsuction connection to chamber 6 is provided by pipe 8 and a similarvacuum or suction connection to space 7 is provided by pipe 9.

In preparing the sheet S for application to the container body, suchsheet is rst positioned on the upper surface 0f the die 5 as shown inFigure 6. Its central portion will rest flat on the upper surface of thedie while its marginal portions will project beyond such upper surfaceand overhang the sides of the die. Suction may be communicated to thechamber 7 to hold the sheet in place on the die while the overhanging orprojecting portions of the sheet are folded down over the sides of thedie successively, the surplus material being taken up by a series ofpleats or folds so that the sheet is caused to closely conform to thedie 5 as shown in Figure 7. This conforming of the sheet to the die maybe accomplished manually or by any appropriate folding or forming meansbut in any event suction communicated to the chambers 6 and 7 eitherbefore, during or after the forming operation will hold the sheet inthis conformity upon the completion thereof.

In practice the sheet S may be preliminarily cut to a contour of exactshape and size necessary to exactly cover the interior surface and upperedges of the body B so as to eliminate the necessity for subsequenttrimming but in practice I prefer to form this sheet well oversize andto trim it after it has been formed, as shown in Figure 7, by trimmingknives 10, as illustrated in Figure 8, which trim from the marginstheexcess 11.`

In Figure 6 it will be noted that the die 5 is mounted upon a member 12which is in effect a cooling plate, provided therein with passages 13through which a cooling medium may be circulated to cool the die andthus keep the surface stratum of the sheet contiguous therewith at alltimes below its fusion or disintegrating point by drawing oif enoughheat from that face of the sheet to accomplish this result. Bycontrolling the temperature of the'water or other medium which iscirculated through the passages 13, the temperature of the die surfacewhich engages the sheet may be accurately regulated and maintained atsuch degree as to preclude fusion thereof and maintain its continuity.In practice it is found convenient to prepare the sheet S forapplication to the body B while the latter is being heated.

After the plastic sheet has been formed as shown in Figure 7 and trimmedas shown in Figure 8 and the container body has been heated to thedesired temperature, these parts .are laminated. This may beconveniently accomplished by means of a combined transfer and api plyingdie 14, such as shown in Figure 9. The die 14 is chambered as shown at15 and suction may be communicated to this chamber through `a pipe 16and made effective upon the inner surface of the die through suctionpassages 17. The die 14 is backed up by a plate 18 having thereinpassages 19 so that the temperature of the die 14 may be controlled.Either a heating or a cooling fluid may be circulated through thepassages 19 as may be desired at different stages of the method.

The die 14, when utilized as a transfer die, is brought into contactwith the exterior face of the hot body B after the die 3 of Figure 5 hasbeen removed therefrom and while the body remains on the hot die 1, sothat the parts appear as shown in Figure 9. Suction is applied to thechamber 15 and causes the article to be gripped by the die 14 so thatsaid die 14 may be moved relative to the die 1 to remove the body B fromsaid die and transfer said body into the position shown in Figure l0wherein it is contacted with the formed sheet on the die 5. Thisoperation is carried on expeditiously so that the interior surface ofthe container body will not appreciably cool and, if desired, the die 14may be a heated die at this time to keep the body hot.

When the relatively cool sheet S is brought into contact with thesurface of the hot body B, and they are pressed together by thecooperating dies S and 14, as shown in Figure l0, the heat of thecontacting surface of the hot body fuses or softens the contiguousstratum of the plastic layer. In some cases, the fusion of the sheet maybe carried only to such a point as to produce a sufficiently tackycondition of the plastic to effect adherence of the sheet to the bodywhen both are restored to room temperature. In other cases, the fusionof the thermoplastic material may be carried so far as to cause thefused and softened plastic to ow into surface conformity with the bodyand enter to some extent into the interstices of the fibrous structurethereof.

The latter procedure may be very efficiently carried out if thecontainer body B is of the smooth die-dried variety, for the surface ofsuch an article is so smooth and even as to Contact with practically allportions of the smooth and even surface of the plastic sheet and it thusrequires very little ow of the plastic to effect the penetrating,interlocking bond which thus occurs. Even with this type of finishmerely a tacky condition may be availed of to form the bond if desired.However, in adhering the sheet to some of the rougher types of containerbody, the tacky condition is recommended and it is not recommended thatany attempt be made to appreciably flow a portion of the thickness of arelatively thin sheet into conformity with a rough, uneven surface,although it may be done with a thicker sheet.

It should be noted that, during the fusion of that portion of theplastic sheet which contacts with the hot body,

the opposite surface stratum of the sheet is kept below its fusion pointby the cooling effect of the relatively cool die 5 with which itcontacts, but this `cooling effect of the die is localized at thissurface of the sheet and does not preclude the amalgamation of the foldswhich were formed in the sheet during the forming step shown in Figure7. In fact, if the material is permitted to flow considerably thecontacting portions of the material in these folds will fuse togetherand become substantially homogeneous. Even when only the tackycondition, hereinbefore referred to, is produced, the folds will besufficiently heated to heat-seal themselves, so that they will notthereafter tend to open or separate.

I have referred to pressure between the ldies 5 and 14 as utilized topress the sheet :and container body into intimate relation with oneanother. If desired, these dies may be provided with some clearancebetween their coacting faces and merely make a firm seal around theedges of the article, so as to permit compressed air, at a temperaturebelow the fusion point of the plastic, to enter into the chamber 7through pipe 9, circulate through passages 7a to the outer surface ofthe die 5 and along the outer surface of such die to passages 6a, andthrough said passages to the chamber 6, to exit through the pipe 8. Ifcompressed air is thus admitted, the sheet will be forced firmly againstthe hot contacting surface of the body B and contact throughout theseparts may thereby be assured.

The use of compressed air in the manner stated may be availed of inapplying the thermoplastic sheet to either roughor smooth finishedcontainer bodies and, irrespective ofthe thickness of the sheet, but itis particularly efiicient in applying relatively thin sheeets to otherthan smooth die-dried surfaces.

lt is also feasible to apply thicker sheets to the rougher surfacedarticles wholly by die pressure and without the use of compressed air asstated, but, when this is done, the sheets should be sufficiently thickto permit substantially all-over surface contact during the fusing stepwith concurrent effective maintenance of the opposite surface strata ofthe sheet below its fusion temperature.

When the sheet S and the body B are superimposed, air

is apt to be trapped therebetween and unless this air is removed, properbonding is practically impossible. For this reason suction should bemaintained within the die 14, through the suction pipe 16, during theentire compositing period, so as to draw such entrained air through thearticle body and thus evacuate it from the article and from between theparts. Moreover, this suction should be maintained throughout the fusionperiod and it is preferably continued until this step is completed andthe assembled body and sheet are removed from the die 14.

After the fusion step has taken place, the die 14 may be immediatelyremoved leaving the composited finished receptacle on the die 5, fromwhich it may be removed by any suitable pick-olf die lor by hand, or, ifdesired, the dies 5 and 14 may be left in assembled relation while thecooling medium is circulated through the passages 19 to lower thetemperature of the entire assembly to a point whereat the thermoplasticwill solidify and set with the parts permanently bound together.Thereafter lthe die 14 may be utilized as a pick-off die to remove thefinished receptacle from the dieS and transfer it to any appropriatedischarge station for packing or otherwise.

Experience with the method hereinbefore described has demonstrated itsefficacy in the production of a strong and durable receptacle absolutelyimpervious to the passage of vapor and moisture and well adapted for thehermetic sealing of the package which it forms. Any suitable cover maybe associated with this receptacle but it is preferably in the form of aflat layer of fibrous material corresponding to the body and havingcomposited v therewith a sheet of thermoplastic material united theretoin the same manner as that employed in compositing the receptacle. Suchcover may be secured in place in any appropriate manner or by anydesired means without departing from this invention, although Ipreferably heatseal it in position on the receptacle.

The foregoing detailed description sets forth the invention in itspreferred practical form, but the invention is to be understood as fullycommensurate with the appended claims.

In the appended claims, reference to a molded fibrous body defines thewell known type or physical character istic of the body as distinguishedfrom the folded sheet paper or cardboard type of product. Hot pressuredie dried finish refers to that characteristic and readily recognizablesmooth surface finish which results from the drying of a wet molded pulpsurface by contact with a hot smooth surfaced die. These terms, as wellas the term fusion-bonded, define the characteristics of the parts andare well understood as such by those working in the pulp molding andplastic arts.

Having thus fully described the invention, what I claim as new anddesire to secure by Letters Patent is:

1. A receptacle comprising: an open top molded fibrous body one face ofwhich is provided with a hot pressure die dried finish, said body havinga bottom and an upstanding peripheral side wall, and a relatively thinpreformed sheet of non-fibrous thermoplastic material permanentlyfusion-bonded directly against the face of said bottom and side wall ofthe body which has the hot pressure die dried finish by the bodycontacting surface stratum of the sheet itself, said sheet being freefrom fusion-caused perforations and forming an impervious seal over thesurface of the body.v

2. A receptacle according to claim 1 comprising: a

fibrous cover having a thermoplastic liner fusion-bonded to the fibrouscover and to the non-fibrous thermoplastic sheet which is attached tothe body to form an impervious seal with said` sheet and hermeticallyseal the receptacle.

3. A receptacle comprising: an open top molded fibrous body having abottom and an opstanding peripheral side wall, and a relatively thinpre-formed sheet of nonfibrous thermoplastic material permanentlyfusion-bonded directly against one surface of said bottom and side wallby the body contacting surface stratum of the sheet itself, said sheetbeing free from fusion-caused perforations and forming an imperviousseal over the surface of said body.

References Cited in the file of this patent UNITED STATES PATENTS2,028,076 Norris Ian. 14, 1936 2,150,910 Chaplin Mar. 21, 1939 2,293,568Snyder Aug, 18, 1942 2,298,421 Salfisberg Oct. 13, 1942 2,319,267 SawyerMay 18, 1943 2,466,966 France et al. Apr. 12, 1949 2,542,413 Ibsch Feb.20, 1951 2,555,380 Stuart et al. June 5, 1951 2,565,336 Adler Aug. 21,1951 2,620,289 Douglas Dec. 2, 1952 2,641,402 Brunn June 9, 1953 FOREIGNPATENTS 103,316 Great Britain June 20, 1936 te* Mp

